Macro wasmtime_option_group 

macro_rules! wasmtime_option_group {
    (
        $(#[$attr:meta])*
        pub struct $opts:ident {
            $(
                $(#[doc = $doc:tt])*
                pub $opt:ident: $container:ident<$payload:ty>,
            )+

            $(
                #[prefixed = $prefix:tt]
                $(#[doc = $prefixed_doc:tt])*
                pub $prefixed:ident: Vec<(String, Option<String>)>,
            )?
        }
        enum $option:ident {
            ...
        }
    ) => { ... };
    (@push Option $dst:ident $val:ident) => { ... };
    (@push Vec $dst:ident $val:ident) => { ... };
}